They would grow even higher with fertilizer and then fall over in a storm. Well it increases the chance or percentage lost to that, it always happens to some degree even with modern varieties.
Which is funny enough, one of the main attributes Borlaug used in the green revolution: crossing Japanese dwarf wheat with modern bread wheat varieties to make the resulting wheat shorter.
The whole idea behind that was that (within reason) the more N you can pump into the crop, the more it will yield, but also the taller it will grow. Wheat is essentially an inverted pendulum when ripe, with about 60% of the above-ground biomass perched at the top.
The main thrust of modern crop breeding has been to create crops that you can successfully get to harvest under high-nutrition environments, without it literally falling over or succumbing to disease due to the turgid, fleshy growth. Even then, if you're applying more than maybe 150kgN/ha, you will be relying on plant growth regulators that inhibit auxin/gibberellin response to keep the plant under control.
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